Interlocking arrangement for a pair of electrical contactors

ABSTRACT

In combination with a first and a second electrical contactor, there is provided interlocking means for preventing simultaneous actuation of the contactors, and means for maintaining the contactors in a fixed spaced relationship and for supporting the interlocking means. The interlocking means is comprised of first and second rigid arms pivotally mounted to the maintaining and supporting means, and first and second electrical switches each having a closed and an open position. The first electrical switch is electrically connected in series with a coil of the second contactor and mechanically interlocked and with an end of the first arm, and the second electrical switch is electrically connected in series with a coil of the first contactor and mechanically interlocked with an end of the second arm. The first arm is mechanically coupled to a movable magnetic member of the first contactor for pivotally moving the first arm between a first and second position in response to movement of the movable magnetic member of the first contactor between the de-energized and the energized position, and the second arm is mechanically coupled to a movable magnetic member of the second contactor for pivotally moving the second arm between a first and a second position in response to movement of the movable magnetic member of the second contactor between the de-energized and the energized position.

' United States Patent [191 Degenhart et a1.

[ Nov. 11, 1975 1 INTERLOCKING ARRANGEMENT FOR A PAIR OF ELECTRICAL CONTACTORS [75] Inventors: Thomas Wayne Degenhart, Normal; Christian De Visser, Clinton, both of 111.

[73] Assignee: General Electric Company, New

Plillltll') E.\'aminer1-laro1d Broome Attorney, Agent, or Firm-S. A. Young; R. A. Cahill; W. C. Bernkopf 57 ABSTRACT In combination with a first and a second electrical contactor. there is provided interlocking means for preventing simultaneous actuation of the contactors. and means for maintaining the contactors in a fixed spaced relationship and for supporting the interlocking means. The interlocking means is comprised of first and second rigid arms pivotally mounted to the maintaining and supporting means. and first and second electrical switches each having a closed and an open position. The first electrical switch is electrically connected in series with a coil of the second contactor and mechanically interlocked and with an end of the first arm. and the second electrical switch is electrically connected in series with a coil of the first contactor and mechanically interlocked with an end of the second arm. The first arm is mechanically coupled to a movable magnetic member of the first contactor for pivotally moving the first arm between a first and second position in response to movement of the movable magnetic member of the first contactor between the de-energized and the energized position. and the second arm is mechanically coupled to a movable magnetic member of the second contactor for pivotall v moving the second arm between a first and a second position in response to movement of the movable magnetic member of the second contactor between the de-energized'and the energized position.

4 Claims. 5 Drawing Figures U.S. Patent Nov. 11, 1975 Sheet2of2 3,919,675

Fie. 5.

TO ENERGY SOURCE To ENERGY souecE INTERLOCKING ARRANGEMENT FOR A PAIR OF ELECTRICAL CONTACTORS BACKGROUND OF THE INVENTION necessary to provide one contactor for controlling the forward direction of the motor, and another contactor for controlling the reverse direction of the motor. If, inadvertently, both contactors were to be simultaneously energized, a short circuit would occur between the motor phases which could result in serious equipment damage.

To avoid this undesired simultaneous actuation of both of the contactors, various interlocking mechanisms have been devised, the majority of which are typified by mechanical interlocking mechanisms described in US. Pat. Nos. 3,233,052 and 3,815,063. In both of these patents, a mechanical interlock is described as providing the restraining force for preventing physical movement of the movable magnetic member of one of the contactors from its de-energized to its energized position if the movable magnetic member of the other contactor has already been moved from its deenergized to its energized position. Reliance on this type of restraining force can result in wear, deformation or dislocation of the mechanical interlocking member or members, which, in turn, could result in binding or other type of failure of the mechanical interlocking arrangement. Furthermore, in order to insure operation of these types of mechanical interlocking arrangements, the positioning and tolerances of the mechanical interlocking members very often are critical, thereby rendering their adoption to be inconvenient and expensive.

OBJECTS OF THE INVENTION It is therefore an object of this invention to provide for an improved interlocking arrangement for a pair of electrical contactors which does not primarily rely upon the mechanical restraint of its interlocking members.

It is another object of this invention to provide for an improved interlocking arrangement for a pair of electrical contactors which utilizes a combination of mechanical and electrical interlocking techniques to provide improved operational and cost performance over previous arrangements described and disclosed in the prior art.

Other objects of the invention will be pointed out hereinafter.

SUMMARY OF THE INVENTION According to a broad aspect of the invention there is provided an improved interlocking arrangement for preventing simultaneous actuation of a pair of electromagnetic contactors. Each contactor is comprised of a stationary magnetic member, a movable magnetic member in juxtaposition with the stationary magnetic member and movable between a de-energized and an energized position, an energizing coil magnetically coupled to the stationary and movable magnetic members, at least one stationary power contact, and at least one movable power contact in juxtaposition with the stationary power contact and mechanically coupled to the movable magnetic member. The interlocking arrangement is comprised of first and second rigid arms pivotally mounted to a member which maintains the contactors in a fixed spaced relationship, and first and second electrical switches each having a closed and an open position. The first rigid arm is mechanically coupled to the movable magnetic member of the first contactor for pivotally moving the first arm between a first and a second position in response to movement of the movable magnetic member of the first contactor between the de-energized and the energized position. The second arm is mechanically coupled to the movable magnetic member of the second contactor for pivotally moving the second arm between a first and a second position in response to movement of the movable magnetic member of the second contactor between the deenergized and the energized position. The first electrical switch is electrically connected in series with the coil of the second contactor and mechanically interlocked with oneend of the first arm, and the second electrical switch is electrically connected in series with the coil of the first contactor and mechanically interlocked with one end of the second arm. When the movable magnetic members of the first and second contactors are in the de-energized position, the first and second arms are positioned to maintain the first and second electrical switches in the closed position. When the movable magnetic member of the first contactor moves to the energized position in response to energization of the coil of the first contactor, the first arm is moved from its first to its second position to cause or allow the first electrical switch to open and thereby prevent energization of the coil of the second contactor, and when the movable magnetic member of the second contactor moves to the energized position in response to energization of the coil of the second contactor, the second arm is moved from its first to its second position to cause or allow the second electrical switch to open and thereby prevent energization of the coil of the first contactor.

Another end of the first arm and another end of the second arm are positioned adjacent each other and each are movable'between an unblocking and a blocking position, whereby when the movable magnetic member of the first contactor moves from the deenergized to the energized position in response to energization of the coil of the first contactor, the other end of the first arm moves from its unblocking to its blocking position, thereby preventing movement of the other end of the second arm from its unblocking to its blocking position and preventing movement of the movable magnetic member of the second contactor from its deenergized to its energized position. Similarly, when the movable magnetic member of the second contactor moves from the de-energized to the energized position in response to energization of the coil of the second contactor, the other end of the second arm moves from its unblocking to its blocking position, thereby preventing movement of the other end of the first arm from its unblocking to its blocking position and also preventing movement of the movable magnetic member of the first contactor from its de-energized to its energized posit1on.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of an interlocking arrangement for a pair of contactors in accordance with the invention;

FIG. 2 is a front elevation view of the interlocking arrangement, as shown in FIG. 1, when both contactors are de-energized;

FIG. 3 is a front elevational view of the interlocking arrangement, as shown in FIG. 1 when one of the contactors is energized;

FIG. 4 is an exploded perspective view of the components of one contactor and one interlocking arm; and

FIG. 5 is an electrical equivalent circuit representation of the energizing circuit for the contactors shown in FIGS. 1 through 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 through 3, the interlocking arrangement in accordance with this invention is comprised of first and second contactors l0 and 12 in combination with interlocking means for preventing simultaneous actuation of the contactors, and a rigid member 14 for maintaining the contactors in a fixed spaced relationship and for supporting the interlocking means. Contactors and 12 are virtually identical, and each can be comprised of standard contactor components of devices commercially available, which devices could be modified to provide mechanical coupling between the interlocking means and a movable magnetic member of each contactor.

Referring to FIG. 4, each contactor is comprised of a standard E-shaped stationary magnetic member 16, a movable magnetic member 18 in juxtaposition with stationary magnetic member 16 and movable between a de-energized and an energized position, an energizing coil 20 having a rectangular slot 22 therein for receiving a medial leg 24 of stationary magnetic member 16, stationary power contacts 26, external terminals 28 each electrically connected. to a respective one of contacts 26, and movable power contacts 30 each in juxtaposition with a respective stationary contact and mechanically coupled to movable magnetic member 18 via a movable armature assembly 32. Coil 20 is magnetically coupled to the stationary and movable magnetic members. Movable magnetic member 18 has a pair of flanged sections 34 and 36 attached to respective opposite sides of member 18 and extending inwardly therefrom to be received in dove-tail sliding engagement within respective grooves 38 and 40, which grooves extend within opposite sides of a lower vertical section 42 of movable armature assembly 32 so as to insure that the combination of movable armature assembly 32 and movable magnetic member 18 move in unison in the vertical direction. Movable contacts 30 are each attached to a respective one of contact bridges 44, wherein each bridge is maintained within a bottom ledge of a respective window 46, within an upper portion 48 of the movable armature assembly, by a respective one of tip springs 50 which extend between a contact bridge and an upper surface bounding the window. The stationary and external contacts are supported within isolated compartments formed within a molded plastic arc chute 52 of the general type used in contactors described in U.S. Pat. No. 3,806,849, entitled Small Definite Purpose Contactors, invented by Philip G. Hughes, and assigned to the same assignee as the assignee of the present invention. When energizing coil 20 is de-energized, movable magnetic member 18 is maintained in a de-energized position and spaced from the pole faces 54 of stationary magnetic member 16, and each of movable contacts 30 is maintained spaced from a respective one of stationary contacts 26, by a pair of return springs 56 and 58. Spring 56 is positioned between an undersurface 60 of upper portion 48 of movable armature assembly 32 and a ledge 62 positioned adjacent an outer wall 64 of molded arc chute 52, and spring 58 is oppositely positioned between an undersurface 66 of upper portion 48 of armature assembly 32 and a ledge 68 positioned adjacent an outer wall 70 of the arc chute. When coil 20 is energized, movable magnetic member 18 moves towards stationary magnetic member 16 and to its energized position, at which time, each of the respective movable and stationary contacts are in sealing engagement. The operation of the components of the contactor described above is conventional and similar to the operation of the contactor described in U.S. Pat. No. 3,806,849.

The interlocking means is comprised of first and second rigid arms 72 and 74 and first and second normally open momentary contact lever operated switches 76 and 78 (all shown in FIGS. 1, 2, and 3), and first and second means for mechanically coupling respective first and second anns 72 and 74 to the movable magnetic members of respective contactors 10 and 12. First and second arms 72 and 74 are fixed to a medial vertically extending portion 80 of supporting member 14 for insuring pivotal movement of the respective first and second arms about respective first and second mounting pins 82 and 84. Referring now to FIG. 4, a means for coupling arm 74 to the movable magnetic member of contactor 12 is provided by a pin 86, which energizes a hole 87 in movable magnetic member 18, having a tapped hole 88 therein for receiving a machine screw 90, which machine screw passes through a hole 92 in an upwardly protruding medial portion 94 of arm 74. This insures that one end 96 of arm 74 pivotally moves clockwise between a first and a second position in response to movement of the movable magnetic member of contactor 12 between the de-energized and the energized position. Although not shown, arm 72 is similarly coupled to the movable magnetic member of contactor 10, wherein one end 98 of arm 72 pivotally moves counter-clockwise between a first and a second position in response to movement of the movable magnetic member of contactor 10 between its de-energized and its energized position. Momentary contact switches 76 and 78 are mounted to respective vertically extending end portions 100 and 102 using standard fastening and mounting techniques. As shown in FIG. 5, normally open momentary contact switch 76 and coil 20 of contactor 12 are electrically connected in series to an energy source, while normally open momentary switch 78 and an energizing coil 104 of contactor 10 are also electrically connected in series to an energy source. At the same time, (as shown in FIGS. 1 through 3) a lever 106 of momentary contact switch 76 is mechanically interlocked with end 98 of rigid arm 72, while a lever 108 of momentary contact switch 78 is mechanically interlocked with end 96 of rigid arm 74. The interlocking of arm 72 with lever 106 of switch 76 provides that when end 98 of arm 72 is maintained in the first posi tion, when the movable magnetic member of contactor is in the de-energized position, lever 106 is maintained (upward) in a position which insures that normally open switch 76 is closed. Similarly, when end 96 of arm 74 is in its first position, when the movable magnetic member of contactor 12 is in the de-energized position, end 96 of arm 74 holds lever .108 of normally open momentary contact switch 78 in an upward position to insure that switch 78 is closed. Furthermore, when the movable magnetic member of contactor 10 moves to its energized position, end 98 of arm 72 is moved counter-clockwise to its second position, thereby allowing lever 106 to return to its normal position and switch 76 to return to its normally open position. Still further, when the movable magnetic member of contactor 12 moves to its energized position, end 96 of arm .74 moves clockwise to its second position, thereby allowing lever 108 to return to its normal position and switch 78 to return to its normally open position. In this manner, a combination of a mechanical and electrical interlocking arrangement is provided which insures that, when contactor 10 is energized, switch 76, which is in series with the energizing coil of contactor 12, is open, thereby preventing energization of contactor 12. Similarly, when contactor 12 is energized, the mechanical and electrical interlocking arrangement insures that switch 78, which is in series with the coil of contactor 10, is open, thereby preventing energization of contactor 10.

While the above described mechanical and electrical interlocking arrangement serves as and provides the primary system protection, an additional backup or secondary mechanical interlocking arrangement is provided for assuring additional protection only when the primary interlocking mechanism fails due to shortcircuiting of either or both of switches 76 and 78. This secondary mechanical interlocking arrangement is provided by respective end portions 110 and 112 of arms 72 and 74, which end portions move between an unblocking'position when the contactors are de-energized and a blocking position when a respective one of the contactors is energized. This is more clearly shown in FIG. 3, wherein arm 74 has moved in response to movement of the movable magnetic member of contactor 12 from its de-energized to its energized position. Under these circumstances, end 96 of arm 74'moves to its second position and end 112 of arm 74 moves clockwise to its blocking position. Now, if switch 78 develops a short circuit, thereby causing a failure of the primary interlocking mechanism, end portion 112of arm 74, which is in its blocking position, will interfere with and prevent movement of end portion 110 of arm 72 from its unblocking to its blocking position. Since arm 72 is mechanically coupled to the movable magnetic member of contactor 10, the movable magnetic member will not be permitted to move from its de-energized to its energized position even if the coil of contactor 10 is energized. This, in turn, will prevent closure of the movable and stationary contacts of contactor 10, and thus prevent simultaneous actuation of contactors 10 and 12 in the event of failure of the primary interlocking mechanism due to the short-circuiting of switch 78. Similarly, if contactor 10 is energized, end 110 of arm 72 will move counter-clockwise to its blocking position and will interfere with end 112 of arm 74 to prevent movement of arm 74 in the event that switch 76 is short-circuited. Thus, the movable magnetic member of contactor 12 will be prevented from moving from its de-energized to its energized position, which, in turn, will prevent closure of the movable and stationary contacts of contactor 12 and the simultaneous actuation of both contactors l0 and 12.

At this point, it should be noted that supporting member 14 is provided with longitudinally extending vertical sections 114 and 116 to impart rigidity to member 14. It should also be noted, at this point. that contactors 10 and 12 are maintained in a fixed spaced relationship by the fastening of member 14 to respective base plates 118 and 120 of respective contactors l0 and 12 using standard fastening and mounting techniques.

The operation, of the interlocking arrangement for respective contactors 10 and 12 will now be explained. When the energizing coils of contactors 10 and 12 are de-energized, the movable magnetic members of the respective contactors are in the de-energized position. Under these circumstances, respective ends 98 and 96 of respective arms 72 and 74 are positioned to maintain normally open switches 76 and 78 in the closed position. This allows energization of either of contactors 10 and 12. Now, if energy is suddenly applied to the coil of contactor 10, the movable magnetic member of contactor 10 moves to its energized position, thereby causing end 98 of arm 72 to move to its second position, and the other end of arm 72 to move to its blocking position. Under these circumstances, lever 106 of switch 76 is allowed to return to its normal position and switch 76 becomes open. Since switch 76 is connected in series with the coil of contactor 12, contactor 12 can never be energized, unless switch 76 fails in a shortcir'cuited condition. If switch 76 fails in a shortcircuited condition, thereby allowing energization of the coil of contactor 12, the movable magnetic member of contactor 12 is prevented from moving from its deenergized to its energized position, and likewise its stationary movable contacts are prevented from closing, due to the interfering blocking position of end 110 of arm 72, which, in turn, prevents movement of end 1 12 of arm 74 from its unblocking to its blocking position. Similarly, if contactor 12 is energized, and its movable magnetic member moves from its de-energized to its energized position, end 96 of arm 74 moves to its second position and end 112 of arm 74 moves to its blocking position. Movement of end 96 of arm 74 to its second position allows lever 108 to return to its normal position, and switch 78 to return to its normally open position. The opening of switch 78 will thus prevent energization of contactor 10, unless switch 78 fails in the short-circuited condition. If switch 78 fails in the shortcircuited condition, contactor 10 cannot be energized, since end 112 of arm 74 is in a blocking position and prevents movement of end 110 of arm 72 from its unblocking to its blocking position. This, in turn, results in the movable magnetic member of contactor 10 being prevented from moving from its de-energized to its energized position, which, in turn, prevents the closure of its movable and stationary contacts, thereby also preventing the simultaneous actuation of contactors l0 and 12.

Thus, the interlocking arrangement described above not only provides a unique primary interlocking arrangement or mechanism for preventing simultaneous actuation of a pair of contactors, but also provides a secondary or backup mechanical interlocking mechanism which provides additional protection in the event that the primary mechanism fails. This has the advantage that when the primary interlocking mechanism is operating properly, the secondary interlocking mechanism is not being subjected to the stress, abuse, and wear that normal mechanical interlocks in the prior art usually experience. Thus, the secondary interlock, which is normally vulnerable to failure due to continu ous use, is only used in emergencies, thereby providing for an overall interlocking arrangement which is more reliable than those described in the prior art.

Although the invention has been described with reference to a specific embodiment thereof, numerous modifications are possible without departing from the invention, and it is desirable to cover all modifications falling within the spirit and scope of this invention.

What we claim as new and desire to secure by letters patent of the United States is:

1. In combination with a first and a second electromagnetic switching device, are interlocked means for preventing simultaneous actuation of said devices, and means for maintaining said devices in a fixed spaced relationship and for supporting said interlock means:

A. each of said electromagnetic switching devices comprising: I

a. a stationary magnetic member;

b. a movable magnetic member in juxtaposition with said stationary magnetic member and movable between a de-energized and an energized position;

c. an energizing coil magnetically coupled to said stationary and movable magnetic members;

d. at least one stationary power contact; and

e. at least one movable power contact in juxtaposition with said stationary contact and mechanically coupled to said movable magnetic member; and

B. said interlocking means comprising:

a. first and second rigid arms pivotally mountedto said maintaining and supporting means;

b. a first means mechanically coupling said first arm to said movable magnetic member of said first device for pivotally moving said first amt between a first and a second position in response to movement of said movable magnetic member of said first device between the de-energized and the energized position;

c. a second means mechanically coupling said second arm to said movable magnetic member of said second device for pivotally moving said second arm between a first and a second position in response to movement of said movable magnetic member of said second device between the deenergized and the energized position; and' d. first and second electrical switches each having a closed and an open position, said first electrical switch being electrically connected in series with said coil of said second device and mechanically interlocked with a portion of said first am, said second electrical switch being electrically connected in series with said coil of said first device and mechanically interlocked with a portion of said second arm, whereby when said movable magnetic members of said first and second devices are in the de-energized position, said first and second arms are positioned to maintain said first and second electrical switches in the closed position, when said movable magnetic member of said first device moves to the energized position in response energization of said coil of said first device, said first arm being caused to move from its first to its second position to enable said first electrical switch to open and thereby prevent energization of said coil of said second device, and when said movable magnetic member of said second device moves to the energized position in response to energization of said coil of said second device, said second arm is moved from its first to its second position to enable said second electrical switch to open and thereby prevent energization of said coil of said first device.

2. The combination according to claim 1 wherein each of said first and second electrical switches is a normally open momentary contact switch.

3. The combination according to claim 2 wherein said portion of said first arm is an end thereof for holding said first electrical switch in the closed position when said movable magnetic member of said first device is in the de-energized position, and said portion of said second arm is an end thereof for holding said second electrical switch in the closed position when said movable magnetic member of said second device is in the de-energized position.

4. The combination according to claim 3 wherein another end of said first arm and another end of said second arm are positioned adjacent each other and each are movable between an unblocking and a blocking position, whereby when said movable magnetic member of said first device moves from the de-energized to the energized position in response to energization of said coil of said first device, said other end of said first arm moves from its unblocking to its blocking position,

thereby preventing movement of said other end of said second arm, from its unblocking to its blocking position from, the de-energized to the energized position. 

1. In combination with a first and a second electromagnetic switching device, are interlocked means for preventing simultaneous actuation of said devices, and means for maintaining said devices in a fixed spaced relationship and for supporting said interlock means: A. each of said electromagnetic switching devices comprising: a. a stationary magnetic member; b. a movable magnetic member in juxtaposition with said stationary magnetic member and movable between a de-energized and an energized position; c. an energizing coil magnetically coupled to said stationary and movable magnetic members; d. at least one stationary power contact; and e. at least one movable power contact in juxtaposition with said stationary contact and mechanically coupled to Said movable magnetic member; and B. said interlocking means comprising: a. first and second rigid arms pivotally mounted to said maintaining and supporting means; b. a first means mechanically coupling said first arm to said movable magnetic member of said first device for pivotally moving said first arm between a first and a second position in response to movement of said movable magnetic member of said first device between the de-energized and the energized position; c. a second means mechanically coupling said second arm to said movable magnetic member of said second device for pivotally moving said second arm between a first and a second position in response to movement of said movable magnetic member of said second device between the de-energized and the energized position; and d. first and second electrical switches each having a closed and an open position, said first electrical switch being electrically connected in series with said coil of said second device and mechanically interlocked with a portion of said first arm, said second electrical switch being electrically connected in series with said coil of said first device and mechanically interlocked with a portion of said second arm, whereby when said movable magnetic members of said first and second devices are in the de-energized position, said first and second arms are positioned to maintain said first and second electrical switches in the closed position, when said movable magnetic member of said first device moves to the energized position in response energization of said coil of said first device, said first arm being caused to move from its first to its second position to enable said first electrical switch to open and thereby prevent energization of said coil of said second device, and when said movable magnetic member of said second device moves to the energized position in response to energization of said coil of said second device, said second arm is moved from its first to its second position to enable said second electrical switch to open and thereby prevent energization of said coil of said first device.
 2. The combination according to claim 1 wherein each of said first and second electrical switches is a normally open momentary contact switch.
 3. The combination according to claim 2 wherein said portion of said first arm is an end thereof for holding said first electrical switch in the closed position when said movable magnetic member of said first device is in the de-energized position, and said portion of said second arm is an end thereof for holding said second electrical switch in the closed position when said movable magnetic member of said second device is in the de-energized position.
 4. The combination according to claim 3 wherein another end of said first arm and another end of said second arm are positioned adjacent each other and each are movable between an unblocking and a blocking position, whereby when said movable magnetic member of said first device moves from the de-energized to the energized position in response to energization of said coil of said first device, said other end of said first arm moves from its unblocking to its blocking position, thereby preventing movement of said other end of said second arm from its unblocking to its blocking position and preventing movement of said movable magnetic member of said second device from the de-energized to the energized position, and when said movable magnetic member of said second device moves from the de-energized to the energized position in response to energization of said coil of said second device, said other end of said second arm moves from its unblocking to its blocking position, thereby preventing movement of said other end of said first arm from its unblocking to its blocking position and also preventing movement of said movable magnetic member of said first device from the de-energized to the energized position. 